Manufacturing method of nylon
Nylon is a widely used engineering plastic, which is widely used in the field of raw materials for chemical production due to its properties such as high strength, abrasion resistance and chemical resistance. This article will introduce the manufacturing method of nylon, including the steps of polymerization reaction, processing and molding.
I. Polymerization reaction
Nylon is made by polymerization reaction. Polymerization reaction is the process of connecting many small molecule monomers into a large polymer. The monomers of nylon are generally adipic acid and adipic diamine.
1. Adipic acid and adipic diamine are mixed together in a certain molar ratio, and appropriate amounts of water are added to adjust the pH so that a homogeneous salt solution is formed.
2. Under the condition of high temperature and high pressure, by adding catalyst, adipic acid and hexanediamine undergo polycondensation reaction to produce polymer of nylon 66.
3. By controlling the reaction conditions and the use of additives, the molecular weight, molecular weight distribution and other properties of nylon can be adjusted.
Two, processing and molding
Nylon polymer is made, it needs to be processed and molded in order to become a product with practical value. There are various processing and molding methods for nylon, including injection molding, extrusion, blow molding, calendering and so on.
1. Injection molding is the method of adding nylon polymer pellets to an injection molding machine, injecting the molten nylon into a mold by heating and melting, and obtaining products after cooling and curing.
2. Extrusion molding is the method of adding nylon polymer particles into the extruder, by heating and melting, the molten nylon will be extruded through the mold, commonly used in the manufacture of pipes, rods and so on.
3. Blow molding is the method of adding nylon polymer pellets into a blow molding machine, and through heating and melting, blowing the molten nylon into the mold to form hollow products.
4. Calendering is a method of adding nylon polymer particles into a calender, and by heating and melting, the molten nylon is calendered in the calender to form a sheet of a certain thickness.
Three, post-treatment
After processing and molding, nylon products also need to be post-treated to improve their performance and service life. Post-treatment methods include heat treatment, mechanical treatment, chemical treatment and so on.
1. Heat treatment can eliminate the internal stress of the products and improve the crystallinity, improve the mechanical properties and dimensional stability of the products.
2. Mechanical treatment can improve the surface roughness of the products and increase the wear resistance of the surface.
3. Chemical treatment can change the chemical properties of the surface of the product, improve its chemical resistance and adhesion, etc..
In short, the manufacturing method of nylon includes the steps of polymerization reaction, processing and molding, and post-treatment. By controlling the reaction conditions and the processing and molding process, nylon products with different properties and service life can be manufactured to meet the needs of the field of raw materials for chemical production.
